Fix uninitialized memory error caused by r50606.

tools/valgrind/memcheck/suppressions_mac.txt

 # There are three kinds of suppressions in this file:
 # 1. Third party stuff we have no control over.
 #
 # 2. Intentional unit test errors, stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing.
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system.
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 1261 matching lines @@
    fun:rips_f_DrawRing
    fun:rips_f_BltShape
    fun:ripc_Render
    fun:ripc_DrawRects
    fun:CGContextFillRects
    fun:CGContextFillRect
    fun:NSRectFill
    fun:_ZN18FocusIndicationFix40currentOSHasSetFocusRingStyleInBitmapBugEv
 }
 {
-   bug_48269
-   Memcheck:Cond
-   ...
-   fun:-[BrowserWindowController initWithBrowser:takeOwnership:]
-   fun:-[BrowserWindowController initWithBrowser:]
-   fun:_ZN13BrowserWindow19CreateBrowserWindowEP7Browser
-   fun:_ZN7Browser19CreateBrowserWindowEv
-   fun:_ZN7Browser6CreateEP7Profile
-}
-{
    bug_49086
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN26TemplateURLPrepopulateData27MakePrepopulatedTemplateURLEPKwS1_S1_PKcS1_S3_i
    fun:_ZN26TemplateURLPrepopulateData32GetPrepopulatedTemplatefromPrefsEP11PrefServicePSt6vectorIP11TemplateURLSaIS4_EE
    fun:_ZN26TemplateURLPrepopulateData22GetPrepopulatedEnginesEP11PrefServicePSt6vectorIP11TemplateURLSaIS4_EEPm
    fun:_ZN54TemplateURLPrepopulateDataTest_ProvidersFromPrefs_Test8TestBodyEv
  }